The present invention relates generally to the field of vertical lifts, and in particular, lift mechanisms that convert to stairs.
Stairways employed in buildings and other structures present difficulties to non-ambulatory individuals. For example, a non-ambulatory individual confined to a personal vehicle such as a wheelchair cannot easily negotiate common stairwells. To accommodate such individuals, separate elevator lifts, moving chair arrangements, or ramps are often provided. In stair structures extending a vertical distance that is less than a building story, such as those typically used near the entrance to a building, a separate elevator lift is not always practical, particularly in outdoor environments. In such cases, separate ramps or moving chair arrangements may be provided which facilitate vertical travel by a personal vehicle.
One drawback to the use of a separate ramp to provide personal vehicle access to elevated surfaces is that suitable ramps consume relatively large amounts of space. As a result, existing buildings must often be substantially altered to accommodate the installation of a ramp. In many circumstances, space constraints surrounding the building make installation of a ramp impossible.
Moving chair arrangements offer a solution in such low rise environments. Moving chair arrangements comprise a chair that slides diagonally up and down the stair way. Such arrangements require that the personal vehicle be separately transported up or down the stairway. Because personal vehicles can be quite heavy, separate transport of the personal vehicle can be difficult. Moreover, the movable chair itself, when not in use, nevertheless occupies stairway space and dictates the appearance of the staircase.
Separate vertical wheelchair lifts have also been employed for such low rise environments for use in situations in which there is inadequate room for an access ramp. Such devices, however, while consuming less space than a ramp, nevertheless consume valuable access space and dictate architectural parameters. Moreover, separate wheelchair lifts may be impossible to implement in hallways or other narrow environments.
In an attempt to address some of the concerns of the separate vertical lift, lifts have been developed that cooperate with a staircase to provide a lift that fits within a hallway or narrow environment. For example, U.S. Pat. No. 4,457,402 to Del Vecchio et al. shows a lift that is disposed directly in front of a low rise staircase that extends from a lower surface to an upper surface. The lift provides vertical transport of wheelchairs from the lower surface to the level of the upper surface. When the lift rises, the stairs collapse upward to form a bridge platform that allows travel from the lift platform over the area normally occupied by the staircase to the destination upper surface.
Another proposed design of a lift that may be located in a hallway is found in U.S. Pat. No. 5,234,078 to Smith. In the Smith patent, the lift platform is normally located on the upper surface directly behind the ascending stairs. In other words, the lift platform forms a portion of the upper surface. The lift platform provides transport between the upper surface and the lower surface through vertical movement. When the lift platform lowers to the level of the lower surface, the stairs collapse so that they too are substantially on the level of the lower surface. When the lift platforms rises to the level of the upper surface, the stairs reconfigure into a staircase.
A drawback of the designs found in the Del Vecchio et al. and Smith patents discussed above is that they require space equivalent to the area of the lift platform either completely in front of or completely behind the staircase. In some cases, such area is not available. Moreover, because the lift platform is located completely outside the footprint of the staircase, the lift platform creates a potentially displeasing architectural discontinuity with the surface at which it normally rests while not in operation. For example, as shown in FIG. 1 of the Smith patent, the lift structure requires special wall and floor structures that create visible discontinuities along the floor and wall. Likewise, the lift shown in FIG. 1 of the Del Vecchio et al. patent undesirable creates a plainly visible discontinuity along the intersection of the platform and lower (ground) surface. Such discontinuities significantly affect the appearance of an architectural structure.
There exists a need, therefore, for a lift structure for providing access to personal vehicles between a lower surface and an upper surface that has reduced impact on the architectural and/or design aspects of a structure, and may be employed in structures with space constraints.
The present invention fulfills the above need, as well as others, by providing, in one embodiment, a convertible lift mechanism that employs a conversion stair that functions as a stair in one configuration and as a lift platform in another configuration. By employing a stair that converts into a lift platform, the lift platform need not be implemented as a totally separate structure that both occupies additional space and impinges upon the architectural integrity of a structure. In other embodiments, the lift platform is positioned below a number of retractable stairs. In either case, the convertible lift mechanism of the present invention includes a lift platform that occupies space that is already occupied by the staircase, thus requiring little or no additional space. Accordingly, the architectural integrity of the structure is left substantially intact.
In accordance with one embodiment of the present invention, there is provided a convertible lift mechanism for moving an object from a lower surface to a vertically displaced upper surface. The lower surface and the upper surface have a vertical wall interposed therebetween. The convertible lift mechanism includes a lift platform which is movable between (i) a lowered platform position in which the lift platform is positioned approximately level with the lower surface, and (ii) a raised platform position in which the lift platform is positioned approximately level with the upper surface. The convertible lift mechanism also includes a gate member pivotally secured to the lift platform. The gate member is positionable between (i) an extended gate position in which the gate member is orientated substantially parallel to the lift platform so as to form a bridging surface between the lower surface and the lift platform, and (ii) a retracted gate position in which the gate member is orientated substantially perpendicular to the lift platform so as to form a retaining surface for retaining the object on the lift platform. The convertible lift mechanism further includes a number of retractable stairs. Each of the number of retractable stairs includes a substantially horizontal stepping surface. Each of the number of retractable stairs is horizontally movable between (a) a retracted stair position in which the stepping surface is received into an opening defined in the vertical wall, and (b) an extended stair position in which the stepping surface extends out of the opening defined in the vertical wall.
In accordance with another embodiment of the present invention, there is provided a method of operating a convertible lift mechanism for moving an object from a lower surface to a vertically displaced upper surface. The lower surface and the upper surface have a vertical wall interposed therebetween. The convertible lift mechanism has (a) a lift platform, (b) a gate member pivotally coupled to the lift platform, and (c) a number of retractable stairs. The method includes the step of positioning the lift platform in a lowered platform position in which the lift platform is positioned approximately level with the lower surface. The method also includes the step of positioning the gate member in an extended gate position in which the gate member is orientated substantially parallel to the lift platform so as to form a bridging surface between the lower surface and the lift platform. The method further includes the step of positioning each of the number of retractable stairs in an extended stair position in which a stepping surface associated with each of the number of retractable stairs extends out of an opening defined in the vertical wall. In addition, the method includes the step of retracting the stepping surface of each of the number of retractable stairs into the opening defined in the vertical wall so as to position each of the number of retractable stairs into a retracted stair position. Yet further, the method includes the step of positioning the gate member in a retracted gate position in which the gate member is orientated substantially perpendicular to the lift platform so as to form a retaining surface for retaining the object on the lift platform. Moreover, the method includes the step of moving the lift platform from the lowered platform position to a raised platform position in which the lift platform is positioned approximately level with the upper surface.
In accordance with yet another embodiment of the present invention, there is provided a convertible lift mechanism for moving an object from a lower surface to a vertically displaced upper surface. The lower surface and the upper surface have a vertical wall interposed therebetween. The convertible lift mechanism includes a number of retractable stairs. Each of the number of retractable stairs includes a substantially horizontal stepping surface. Each of the number of retractable stairs is horizontally movable between (a) a retracted stair position in which the stepping surface is received into an opening defined in the vertical wall, and (b) an extended stair position in which the stepping surface extends out of the opening defined in the vertical wall. The convertible lift mechanism also includes a lift platform which is movable between (i) a lowered platform position in which the lift platform is positioned approximately level with the lower surface, and (ii) a raised platform position in which the lift platform is positioned approximately level with the upper surface. The convertible lift mechanism also includes a number of vertical screw drive mechanisms. Each of the number of vertical screw drive mechanisms includes a driven lift nut. Each of the driven lift nuts of the number of vertical screw drive mechanisms is secured to the lift platform. Actuation of the number of vertical screw drive mechanisms causes movement of the driven lift nuts thereby moving the lift platform between the lowered platform position and the raised platform position.
In accordance with a further embodiment of the present invention, there is provided a convertible lift mechanism for moving an object from a lower surface to a vertically displaced upper surface. The lower surface and the upper surface have a vertical wall interposed therebetween. The convertible lift mechanism includes a lift platform which is movable between (i) a lowered platform position in which the lift platform is positioned approximately level with the lower surface, and (ii) a raised platform position in which the lift platform is positioned approximately level with the upper surface. The convertible lift mechanism also includes a first retractable stair having a first substantially horizontal stepping surface. The first retractable stair is horizontally movable between (i) a first retracted stair position in which the first stepping surface is received into an opening defined in the vertical wall, and (ii) a first extended stair position in which the first stepping surface extends out of the opening defined in the vertical wall. The convertible lift mechanism further includes a second retractable stair having a second substantially horizontal stepping surface. The second retractable stair being horizontally movable between (i) a second retracted stair position in which the second stepping surface is received into the opening defined in the vertical wall, and (ii) a second extended stair position in which the second stepping surface extends out of the opening defined in the vertical wall. The convertible lift mechanism yet further includes a contact member secured to the first retractable stair. The contact member contacts the second retractable stair during movement of the first retractable stair from the first retracted stair position to the first extended stair position so as to urge the second retractable stair into the second extended stair position, and (ii) the contact member contacts the second retractable stair during movement of the first retractable stair from the first extended stair position to the first retracted stair position so as to urge the second retractable stair into the second retracted stair position.
The use of the convertible lift mechanisms of the present invention affords the ability to provide an alternative transport method at a stairway while requiring little or no additional space.